gem5 v24.0.0.0
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Flash Device model The Flash Device model is a timing model for a NAND flash device. More...
#include <flash_device.hh>
Classes | |
struct | CallBackEntry |
struct | FlashDeviceStats |
struct | PageMapEntry |
Every logical address maps to a physical block and a physical page. More... | |
Public Member Functions | |
FlashDevice (const FlashDeviceParams &) | |
Initialize functions. | |
~FlashDevice () | |
DrainState | drain () override |
Checkpoint functions. | |
void | checkDrain () |
Checkdrain; needed to enable checkpoints. | |
void | serialize (CheckpointOut &cp) const override |
Serialize; needed to create checkpoints. | |
void | unserialize (CheckpointIn &cp) override |
Unserialize; needed to restore from checkpoints. | |
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AbstractNVM (const AbstractNVMParams &p) | |
virtual | ~AbstractNVM () |
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const Params & | params () const |
SimObject (const Params &p) | |
virtual | ~SimObject () |
virtual void | init () |
init() is called after all C++ SimObjects have been created and all ports are connected. | |
virtual void | loadState (CheckpointIn &cp) |
loadState() is called on each SimObject when restoring from a checkpoint. | |
virtual void | initState () |
initState() is called on each SimObject when not restoring from a checkpoint. | |
virtual void | regProbePoints () |
Register probe points for this object. | |
virtual void | regProbeListeners () |
Register probe listeners for this object. | |
ProbeManager * | getProbeManager () |
Get the probe manager for this object. | |
virtual Port & | getPort (const std::string &if_name, PortID idx=InvalidPortID) |
Get a port with a given name and index. | |
virtual void | startup () |
startup() is the final initialization call before simulation. | |
DrainState | drain () override |
Provide a default implementation of the drain interface for objects that don't need draining. | |
virtual void | memWriteback () |
Write back dirty buffers to memory using functional writes. | |
virtual void | memInvalidate () |
Invalidate the contents of memory buffers. | |
void | serialize (CheckpointOut &cp) const override |
Serialize an object. | |
void | unserialize (CheckpointIn &cp) override |
Unserialize an object. | |
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EventQueue * | eventQueue () const |
void | schedule (Event &event, Tick when) |
void | deschedule (Event &event) |
void | reschedule (Event &event, Tick when, bool always=false) |
void | schedule (Event *event, Tick when) |
void | deschedule (Event *event) |
void | reschedule (Event *event, Tick when, bool always=false) |
void | wakeupEventQueue (Tick when=(Tick) -1) |
This function is not needed by the usual gem5 event loop but may be necessary in derived EventQueues which host gem5 on other schedulers. | |
void | setCurTick (Tick newVal) |
EventManager (EventManager &em) | |
Event manger manages events in the event queue. | |
EventManager (EventManager *em) | |
EventManager (EventQueue *eq) | |
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Serializable () | |
virtual | ~Serializable () |
void | serializeSection (CheckpointOut &cp, const char *name) const |
Serialize an object into a new section. | |
void | serializeSection (CheckpointOut &cp, const std::string &name) const |
void | unserializeSection (CheckpointIn &cp, const char *name) |
Unserialize an a child object. | |
void | unserializeSection (CheckpointIn &cp, const std::string &name) |
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DrainState | drainState () const |
Return the current drain state of an object. | |
virtual void | notifyFork () |
Notify a child process of a fork. | |
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Group (Group *parent, const char *name=nullptr) | |
Construct a new statistics group. | |
virtual | ~Group () |
virtual void | regStats () |
Callback to set stat parameters. | |
virtual void | resetStats () |
Callback to reset stats. | |
virtual void | preDumpStats () |
Callback before stats are dumped. | |
void | addStat (statistics::Info *info) |
Register a stat with this group. | |
const std::map< std::string, Group * > & | getStatGroups () const |
Get all child groups associated with this object. | |
const std::vector< Info * > & | getStats () const |
Get all stats associated with this object. | |
void | addStatGroup (const char *name, Group *block) |
Add a stat block as a child of this block. | |
const Info * | resolveStat (std::string name) const |
Resolve a stat by its name within this group. | |
void | mergeStatGroup (Group *block) |
Merge the contents (stats & children) of a block to this block. | |
Group ()=delete | |
Group (const Group &)=delete | |
Group & | operator= (const Group &)=delete |
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Named (const std::string &name_) | |
virtual | ~Named ()=default |
virtual std::string | name () const |
Private Types | |
enum | Actions { ActionRead , ActionWrite , ActionErase , ActionCopy } |
Defines the possible actions to the flash. More... | |
Private Member Functions | |
void | initializeMemory (uint64_t disk_size, uint32_t sector_size) override |
Device access functions Inherrited from AbstractNVM. | |
void | readMemory (uint64_t address, uint32_t amount, const std::function< void()> &event) override |
Access functions Access function to simulate a read/write access to the memory. | |
void | writeMemory (uint64_t address, uint32_t amount, const std::function< void()> &event) override |
void | initializeFlash (uint64_t disk_size, uint32_t sector_size) |
Initialization function; called when all disk specifics are known. | |
void | accessDevice (uint64_t address, uint32_t amount, const std::function< void()> &event, Actions action) |
Flash action function. | |
void | actionComplete () |
Event rescheduler. | |
Tick | remap (uint64_t logic_page_addr) |
FTL functionality. | |
Tick | accessTimes (uint64_t address, Actions accesstype) |
Access time calculator. | |
void | clearUnknownPages (uint32_t index) |
Function to indicate that a page is known. | |
bool | getUnknownPages (uint32_t index) |
Function to test if a page is known. | |
Private Attributes | |
uint64_t | diskSize |
Disk sizes in bytes. | |
const uint32_t | blockSize |
const uint32_t | pageSize |
const uint32_t | GCActivePercentage |
Garbage collection algorithm emulator. | |
const Tick | readLatency |
Access latencies. | |
const Tick | writeLatency |
const Tick | eraseLatency |
const enums::DataDistribution | dataDistribution |
Flash organization. | |
const uint32_t | numPlanes |
struct FlashDeviceStats | stats |
RequestHandler stats. | |
uint32_t | pagesPerBlock |
Disk dimensions in pages and blocks. | |
uint32_t | pagesPerDisk |
uint32_t | blocksPerDisk |
uint32_t | planeMask |
std::vector< uint32_t > | unknownPages |
when the disk is first started we are unsure of the number of used pages, this variable will help determining what we do know. | |
std::vector< struct PageMapEntry > | locationTable |
address to logic place has a block and a page field | |
std::vector< uint32_t > | blockValidEntries |
number of valid entries per block | |
std::vector< uint32_t > | blockEmptyEntries |
number of empty entries | |
std::vector< std::deque< struct CallBackEntry > > | planeEventQueue |
This vector of queues keeps track of all the callbacks per plane. | |
EventFunctionWrapper | planeEvent |
Completion event. | |
Additional Inherited Members | |
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typedef SimObjectParams | Params |
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static void | serializeAll (const std::string &cpt_dir) |
Create a checkpoint by serializing all SimObjects in the system. | |
static SimObject * | find (const char *name) |
Find the SimObject with the given name and return a pointer to it. | |
static void | setSimObjectResolver (SimObjectResolver *resolver) |
There is a single object name resolver, and it is only set when simulation is restoring from checkpoints. | |
static SimObjectResolver * | getSimObjectResolver () |
There is a single object name resolver, and it is only set when simulation is restoring from checkpoints. | |
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static const std::string & | currentSection () |
Gets the fully-qualified name of the active section. | |
static void | generateCheckpointOut (const std::string &cpt_dir, std::ofstream &outstream) |
Generate a checkpoint file so that the serialization can be routed to it. | |
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Drainable () | |
virtual | ~Drainable () |
virtual void | drainResume () |
Resume execution after a successful drain. | |
void | signalDrainDone () const |
Signal that an object is drained. | |
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const SimObjectParams & | _params |
Cached copy of the object parameters. | |
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EventQueue * | eventq |
A pointer to this object's event queue. | |
Flash Device model The Flash Device model is a timing model for a NAND flash device.
It doesn't tranfer any data
Definition at line 57 of file flash_device.hh.
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Defines the possible actions to the flash.
Enumerator | |
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ActionRead | |
ActionWrite | |
ActionErase | |
ActionCopy | A copy involves taking all the used pages from a block and store it in another. |
Definition at line 74 of file flash_device.hh.
gem5::FlashDevice::FlashDevice | ( | const FlashDeviceParams & | p | ) |
Initialize functions.
Flash Device constructor and destructor.
Definition at line 65 of file flash_device.cc.
References actionComplete().
gem5::FlashDevice::~FlashDevice | ( | ) |
Definition at line 145 of file flash_device.cc.
References DPRINTF.
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Flash action function.
Handles the accesses to the device.
The function determines when certain actions are scheduled and schedules an event that uses the callback function on completion of the action.
The access will be broken up in a number of page accesses. The number of page accesses depends on the amount that needs to be transfered. The assumption here is that the interface is completely ignorant of the page size and that this model has to figure out all of the transaction characteristics.
Check if the page is known and used. unknownPages is a bitmap of all the pages. It tracks wether we can be sure that the information of this page is taken into acount in the model (is it considered in blockValidEntries and blockEmptyEntries?). If it has been used in the past, then it is known.
previous part of the function found the times spend in different planes, now lets find the maximum to know when to callback the disk
If there are no events for this plane, then add the current time to the occupation time; otherwise, plan it after the last event. If by chance that event is handled in this tick, then we would still end up with the same result.
Definition at line 156 of file flash_device.cc.
References accessTimes(), ActionRead, ActionWrite, gem5::QARMA::amount, blockEmptyEntries, blockValidEntries, clearUnknownPages(), gem5::X86ISA::count, gem5::curTick(), DPRINTF, gem5::MipsISA::event, gem5::FlashDevice::FlashDeviceStats::fileSystemAccess, getUnknownPages(), gem5::MipsISA::index, locationTable, numPlanes, pageSize, pagesPerBlock, planeEvent, planeEventQueue, planeMask, gem5::FlashDevice::FlashDeviceStats::readAccess, gem5::FlashDevice::FlashDeviceStats::readLatency, remap(), gem5::EventManager::reschedule(), gem5::statistics::DistBase< Derived, Stor >::sample(), gem5::EventManager::schedule(), gem5::Event::scheduled(), stats, gem5::FlashDevice::CallBackEntry::time, gem5::Event::when(), gem5::FlashDevice::FlashDeviceStats::writeAccess, and gem5::FlashDevice::FlashDeviceStats::writeLatency.
Referenced by readMemory(), and writeMemory().
Access time calculator.
Calculates the accesstime per operation needed.
Just read the page
Write the page, and read the result
Erase and check wether it was successfull
Copy every valid page
Definition at line 395 of file flash_device.cc.
References ActionCopy, ActionErase, ActionRead, ActionWrite, blockValidEntries, DPRINTF, eraseLatency, readLatency, and writeLatency.
Referenced by accessDevice(), and remap().
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Event rescheduler.
When a plane completes its action, this event is triggered.
When a callback function was associated with that event, it will be called.
Search for a callback that is supposed to happen in this Tick
Invariant: All queued events are scheduled in the present or future.
To ensure that the follow-up action is executed correctly, the callback entry first need to be cleared before it can be called.
Found a callback, lets make it happen
Find when to schedule the planeEvent next
Schedule the next plane that will be ready (if any)
Definition at line 281 of file flash_device.cc.
References checkDrain(), gem5::curTick(), DPRINTF, numPlanes, planeEvent, planeEventQueue, gem5::EventManager::reschedule(), and gem5::Event::when().
Referenced by FlashDevice().
void gem5::FlashDevice::checkDrain | ( | ) |
Checkdrain; needed to enable checkpoints.
Definition at line 570 of file flash_device.cc.
References gem5::curTick(), DPRINTF, gem5::Draining, gem5::Drainable::drainState(), planeEvent, gem5::Drainable::signalDrainDone(), and gem5::Event::when().
Referenced by actionComplete().
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Function to indicate that a page is known.
clearUnknownPages.
defines that a page is known and used unknownPages is a bitmap of all the pages. It tracks wether we can be sure that the information of this page is taken into acount in the model (is it considered in blockValidEntries and blockEmptyEntries?). If it has been used in the past, then it is known. But it needs to be tracked to make decisions about write accesses, and indirectly about copy actions. one unknownPage entry is a 32 bit integer. So if we have a page index, then that means that we need entry floor(index/32) (index >> 5) and we need to select the bit which number is equal to the remainder of index/32 (index%32). The bit is cleared to make sure that we see it as considered in the future.
Definition at line 445 of file flash_device.cc.
References gem5::MipsISA::index, and unknownPages.
Referenced by accessDevice().
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Checkpoint functions.
Drain; needed to enable checkpoints.
Implements gem5::Drainable.
Definition at line 554 of file flash_device.cc.
References DPRINTF, gem5::Drained, gem5::Draining, planeEvent, and gem5::Event::scheduled().
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Function to test if a page is known.
getUnknownPages.
Verify wether a page is known
Definition at line 456 of file flash_device.cc.
References gem5::MipsISA::index, and unknownPages.
Referenced by accessDevice().
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Initialization function; called when all disk specifics are known.
Initiates all the flash functions: initializes the lookup tables, age of the device, etc.
This can only be done once the disk image is known. Thats why it can't be done in the constructor.
Sanity information: check flash configuration
Garbage collection related
This is a bitmap. Every bit is a page unknownPages is a vector of 32 bit integers. If every page was an integer, the total size would be pagesPerDisk; since we can map one page per bit we need ceil(pagesPerDisk/32) entries. 32 = 1 << 5 hence it will do to just shift pagesPerDisk five positions and add one. This will allocate one integer to many for this data structure in the worst case.
Definition at line 103 of file flash_device.cc.
References blockEmptyEntries, blockSize, blocksPerDisk, blockValidEntries, gem5::X86ISA::count, dataDistribution, diskSize, DPRINTF, locationTable, pageSize, pagesPerBlock, pagesPerDisk, and unknownPages.
Referenced by initializeMemory().
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Device access functions Inherrited from AbstractNVM.
Implements gem5::AbstractNVM.
Definition at line 118 of file flash_device.hh.
References initializeFlash().
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Access functions Access function to simulate a read/write access to the memory.
Once the action has completed, the Callback event should be called. Putting a NULL pointer as callback is valid syntax, and should result in the simulation of the access, but with no callback to the higher layer. This may be used to occupy the device, such that next actions will be delayed. The read/write function will schedule the incoming requests on a first come first serve basis.
address | The logical address to a location in the Non-volatile memory. |
amount | The amount of data transfered from the NVM in bytes |
event | A pointer to a callback function that will perform the actions taken by the disk controller on successfull completion of the data transfer between the disk and the disk controller. |
Implements gem5::AbstractNVM.
Definition at line 124 of file flash_device.hh.
References accessDevice(), ActionRead, gem5::QARMA::amount, and gem5::MipsISA::event.
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FTL functionality.
Handles the remapping of the pages.
It is a (I hope) sensible statistic approach. asumption: garbage collection happens when a clean is needed (may become stochastic function).
Are there any empty left in this Block, or do we need to do an erase
Definition at line 342 of file flash_device.cc.
References accessTimes(), ActionCopy, ActionErase, ActionWrite, blockEmptyEntries, gem5::X86ISA::count, DPRINTF, GCActivePercentage, locationTable, pagesPerBlock, pagesPerDisk, stats, and gem5::FlashDevice::FlashDeviceStats::totalGCActivations.
Referenced by accessDevice().
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Serialize; needed to create checkpoints.
Implements gem5::Serializable.
Definition at line 507 of file flash_device.cc.
References blockEmptyEntries, blockValidEntries, gem5::X86ISA::count, gem5::csprintf(), locationTable, gem5::paramOut(), planeMask, SERIALIZE_CONTAINER, SERIALIZE_SCALAR, and unknownPages.
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Unserialize; needed to restore from checkpoints.
Implements gem5::Serializable.
Definition at line 530 of file flash_device.cc.
References blockEmptyEntries, blockValidEntries, gem5::X86ISA::count, gem5::csprintf(), locationTable, gem5::paramIn(), planeMask, unknownPages, UNSERIALIZE_CONTAINER, and UNSERIALIZE_SCALAR.
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Implements gem5::AbstractNVM.
Definition at line 131 of file flash_device.hh.
References accessDevice(), ActionWrite, gem5::QARMA::amount, and gem5::MipsISA::event.
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number of empty entries
Definition at line 196 of file flash_device.hh.
Referenced by accessDevice(), initializeFlash(), remap(), serialize(), and unserialize().
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Definition at line 161 of file flash_device.hh.
Referenced by initializeFlash().
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Definition at line 182 of file flash_device.hh.
Referenced by initializeFlash().
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number of valid entries per block
Definition at line 194 of file flash_device.hh.
Referenced by accessDevice(), accessTimes(), initializeFlash(), serialize(), and unserialize().
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Flash organization.
Definition at line 173 of file flash_device.hh.
Referenced by initializeFlash().
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Disk sizes in bytes.
Definition at line 160 of file flash_device.hh.
Referenced by initializeFlash().
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Definition at line 170 of file flash_device.hh.
Referenced by accessTimes().
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Garbage collection algorithm emulator.
Definition at line 165 of file flash_device.hh.
Referenced by remap().
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address to logic place has a block and a page field
Definition at line 192 of file flash_device.hh.
Referenced by accessDevice(), initializeFlash(), remap(), serialize(), and unserialize().
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Definition at line 174 of file flash_device.hh.
Referenced by accessDevice(), and actionComplete().
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Definition at line 162 of file flash_device.hh.
Referenced by accessDevice(), and initializeFlash().
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Disk dimensions in pages and blocks.
Definition at line 180 of file flash_device.hh.
Referenced by accessDevice(), initializeFlash(), and remap().
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Definition at line 181 of file flash_device.hh.
Referenced by initializeFlash(), and remap().
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Completion event.
Definition at line 202 of file flash_device.hh.
Referenced by accessDevice(), actionComplete(), checkDrain(), and drain().
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This vector of queues keeps track of all the callbacks per plane.
Definition at line 199 of file flash_device.hh.
Referenced by accessDevice(), and actionComplete().
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Definition at line 184 of file flash_device.hh.
Referenced by accessDevice(), serialize(), and unserialize().
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RequestHandler stats.
Definition at line 177 of file flash_device.hh.
Referenced by accessDevice(), and remap().
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when the disk is first started we are unsure of the number of used pages, this variable will help determining what we do know.
Definition at line 190 of file flash_device.hh.
Referenced by clearUnknownPages(), getUnknownPages(), initializeFlash(), serialize(), and unserialize().
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Definition at line 169 of file flash_device.hh.
Referenced by accessTimes().